Heretofore, a grommet is attached to a wire harness to be arranged from an engine room in a motor vehicle to a passenger room. The grommet is installed in a through-hole in a vehicle body panel that partitions a vehicle body into an engine room and a passenger room to protect the wire harness passing the through-hole and to waterproof, dustproof, sound-insulate the passenger room from the engine room.
The present applicant has provided a so-called one-motion grommet in which a vehicle body engagement annular recess provided on an outer periphery of the grommet is engaged with a peripheral edge around the through-hole in the vehicle body panel merely by pushing the grommet into the through-hole from one side.
The one-motion grommet has been disclosed in JP 2002-171644 A. As shown in FIG. 7, a large diameter tubular section 101 of a grommet 100 is provided on an outer peripheral surface with projecting portions 102 so that a contact area between the large diameter tubular section and an inner peripheral surface around a through-hole Hp in a vehicle body panel P is decreased in order to reduce a force for inserting the grommet 100 into the through-hole Hp.
Further, each of the projecting portions 102 changes a slant angle at point P1 that contacts the inner peripheral surface around the through-hole Hp so as to decrease a projecting amount of the projecting portion, and further changes a slant angle at a point P2 that is the same height as a side wall 103a of a vehicle body engagement annular recess 103 so as to be in parallel to an axial direction of the large diameter tubular section 101, namely to be a horizontal direction in FIG. 7.
The inserting force can be reduced by gradually decreasing the projecting amount of the projecting portion 102 toward the vehicle body engagement annular recess 103.
Patent Document 1: JP 2002-171644 A